 In 1996 APM spun out further business called Digitivity, with offices in Cambridge UK and Palo Alto, California, USA to develop an Internet browser security product.In 1998 APM and Digitivity were acquired by Citrix Systems of Ft Lauderdale, Florida, USA and Herbert took up the position of Director for Advanced Technologies where he remained until joining Microsoft in 2001.Herbert published several books and articles, a selection